安全、优雅地从向量中删除特定元素
我想从向量中排除指定列表中的元素，即删除出现在排除列表中的该向量的元素。
我不知道元素是否已经丢失，因此通过 -which(v %in% excepts) 删除元素（如下所示）会导致整个向量在它们未出现的情况下被清除那个向量。
我怎样才能以安全且优雅的方式做到这一点？我是否必须使用布尔（逻辑）掩码，或者是否有我缺少的更优雅的方式？
v <- c("things", "sometimes", "go", "awry", "quickly")
excludes <- c("sometimes", "quickly")
v <- v[-which(v %in% excludes)]
v
# "things" "go" "awry"
which(v %in% excludes)
# Here `excludes` has already been removed, so v is cleared
v <- v[-which(v %in% excludes)]
v
# character(0)
布尔掩码方法
v <- c("things", "sometimes", "go", "awry", "quickly")
excludes <- c("sometimes", "quickly")
v <- v[!v %in% excludes]
v <- v[!v %in% excludes] # perform the removal a second time
v # contains desired value
# "things" "go" "awry"
I would like to exclude elements in a specified list from a vector, i.e. remove elements of that vector which appear in the exclusion list.
I don't know if the elements are already missing, so dropping elements via -which(v %in% excludes) as below causes the entire vector to be cleared in the case that they do not appear in that vector.
How can I do this in a safe and elegant way? Should I necessarily use a boolean (logical) mask or is there a more elegant way I am missing?
v <- c("things", "sometimes", "go", "awry", "quickly")
excludes <- c("sometimes", "quickly")
v <- v[-which(v %in% excludes)]
v
# "things" "go" "awry"
which(v %in% excludes)
# Here `excludes` has already been removed, so v is cleared
v <- v[-which(v %in% excludes)]
v
# character(0)
Boolean mask approach
v <- c("things", "sometimes", "go", "awry", "quickly")
excludes <- c("sometimes", "quickly")
v <- v[!v %in% excludes]
v <- v[!v %in% excludes] # perform the removal a second time
v # contains desired value
# "things" "go" "awry"
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如果没有重复项，请使用
setdiff或对于重复项，使用
vsetdiffIf there are no duplicates, use
setdiffOr with duplicates,
vsetdiff